Make some internal utils functions private

[wtbarnes]

Fixes #330
Fixes #331

This reduces the visibility of some utils functions that are used internally.

[codecov]

Codecov Report

Attention: Patch coverage is 94.44444% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.55%. Comparing base (f996aea) to head (f0de2e9).
Report is 14 commits behind head on main.

Files with missing lines	Patch %	Lines
fiasco/util/setup_db.py	91.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #332      +/-   ##
==========================================
+ Coverage   90.54%   90.55%   +0.01%     
==========================================
  Files          40       41       +1     
  Lines        3394     3400       +6     
==========================================
+ Hits         3073     3079       +6     
  Misses        321      321              

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